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Quick Freezing of Daphnia
>>Wonder if you can freeze them in ice cube form for use later?
>You can freeze them in ice cube trays, but they tend to lose their >food
>content rather quickly once thawed, so feed them fast.
>And since they don't move around, a lot of fish tend to ignore them
>(especially bigger fish/reptiles/amphibians that would normally eat >them
>if they moved).
I would strongly suggest you use flatpacks and not icecubes as the volume of
icecubes is too large. It will take too long time before the animals get
frozen; as a result you will have the formation of a small amount of
ice-nuclei, which become bigger and bigger. These will form big icecrystals
which will then puncture the cell walls and as a result the cell fluids will
leach from the cells. This will lower the nutritional value of the animals
dramatically on one side and will increase the organic load of the water on
the other side.
Try to make as thin a layer as possible in order to achieve quick freezing
(so more ice-nuclei will form, resulting in smaller ice-crystals, resulting
in less damage to the product). Use plastic bags in order to prevent freezer
burn and try to lower the temperature of the freezer compartment. With some
practice you should end up with correctly frozen Daphnia, i.e. still
retaining its nutrients. But of course, live Daphnia are better as their
movement stimulates/triggers the hunting behaviour of many fish.
Biologist San Francisco Bay Brand
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